The subject matter of the invention concerns new 2-amino-6-chloro-4-nitrophenol derivatives, processes for their production and hair dye compositions which contain 2-amino-6-chloro-4-nitrophenol derivatives as direct dyeing nitro dyes.
Nitro dyes have attained a substantial importance for hair dyeing. Hair dye compositions which are capable of dyeing in natural or fashionable shades without the addition of oxidizing agents can be produced by means of combining different nitro dyes. The nitro dyes are also important components of oxidizing hair dye compositions in which they are utilized for rounding off the dyeing results and for producing fashionable effects.
Such nitro dyes which can impart an intensive red coloring to the hair are required in particular for producing fashionable red effects.
For a long time, 2-nitro-p-phenylenediamine was used for this purpose, but it has been objected to recently on toxicological grounds.
A whole series of demands have been made on dyes to be used for dyeing human hair. They must be unobjectionable in both toxicological and dermatological respects.
Moreover, a good fastness to light, acid and friction is required for the hair dye. Its use in oxidizing hair dye compositions further requires that the nitro dyes be stable against hydrogen peroxide in ammoniacal solution and against antioxidants.
A nitro dye which is suitable as an addition to oxidative hair dye compositions must also dye the hair root with sufficient intensity, the latter being less damaged compared to the hair tips. Meeting this demand is very important for achieving a balanced dyeing result, e.g. in the coupler-developer substance combinations of 4-aminophenol and 2,4-diaminoanisole or 4-amino-3-methylphenol and 2,4-diaminoanisole which are usually frequently used. In a dye test, the more damaged hair tips are dyed a deeper red than the less damaged hair roots with such a combination. In order to balance this dyeing behavior, nitro dyes which preferably dye the hair root must be added to the hair dye compositions.
An example of such a nitro dye is 2-nitro-1,4-diaminobenzene. The dye colors the hair an intense neutral red. But it has the disadvantage that it is not favorably stable in storage, particularly in the presence of reducing agents such as ascorbic acid. Moreover, 2-nitro-1,4-diaminobenzene is mutagenic.